NMR-based micrometabolic profiling of plant cells

Laser-assisted microdissection techniques recently have been introduced into various disciplines of plant science, including micrometabolic profiling (Hölscher and Schneider, 2008, Prog. Bot. 69, 141-167; Moco et al., 2009, J. Proteome Res. 8, 1694-1703). We developed methods to analyze laser-microdissected samples by NMR spectroscopy and mass spectrometry. For example, cell-specific metabolic profiles of special cells harvested from the bark of Norway spruce (Picea abies) (Li et al., 2007, Planta 225, 771–779) were determined. Simultaneously, we reported laser-microdissection and NMR analysis of secretory cavities from fresh leaves and herbarium specimen of Dilatris plants (Haemodoraceae) (Hölscher and Schneider, 2007, Planta 225, 767–770). In both studies, the laser-harvested cells were transferred to a NMR tube and 1H and 2D NMR spectra were measured using a cryogenically cooled probehead. The structures of the major metabolites were identified by comparing NMR spectra of the cell extracts with those of authentic reference compounds. In addition to identification, quantification of the major metabolites in the sclereids and sclereid-surrounding cells from Norway spruce was performed. Further examples of combined laser-microdissection and spectroscopic analysis have been reported (Hölscher et al., 2009, Plant J. 60, 907-918) and others are in progress.